Straight edge clamps are well known for use in making straight cuts with for example a circular saw, or for guiding a router on materials, such as wood, aluminum plastic, etc. Straight edge clamps provide a straight edge secured to a work piece or work pieces so that a power tool or a guide for a power tool can be moved along the straight edge, for example, to form a cut edge with a circular hand saw or to form a trimmed edge with a hand router. Also, straight edge clamps are used for the purpose of holding accessory tools against a work piece.
U.S. Pat. No. 6,622,997 discloses a typical straight edge clamp. The straight edge clamp disclosed in the '997 patent includes a straight edge that is made of extruded aluminum and has an open channel, a fixed stop, a sliding stop that is received in the channel and can slide along the straight edge, and a bar or rod clamp that connects the sliding stop to the fixed stop. The bar extends the length of the straight edge.
The sliding stop has a body that is inserted in the channel of the straight edge, and a jaw that protrudes from the body and out of the channel to secure a work piece. The rod and interaction of the sliding stop perform the clamping function. In the locked state, the sliding stop can move toward the fixed stop since the body pushes the locking elements, a series of plates mounted on the rod, near the center of the rod and the pushing force is applied uniformly around the hole, and the locking elements can slide along the rod. However, moving in reverse direction is blocked since the slider pushes the ends of the locking element and the pushing force is applied at a point offset from the center of the holes and the rod, thereby locking the holes on the rod.
The main problem with known straight edge clamps is the need for the rod extending the length of the straight edge and the locking elements. The rod and the locking elements increase the cost of the clamp and the weight. The need for the rod also defines the length of the clamp. The clamp has a predetermined length that cannot be adjusted. The clamp length cannot be changed. Additionally, the clamp cannot be folded, since the rod is rigid and prevents any change in the length of the straight edge.